Cleaning Appliance, in Particular Vacuum Cleaner

ABSTRACT

A cleaning appliance, in particular vacuum cleaner. The appliance comprises a filter and a heating device, by means of which the filter can be heated to carry out a pyrolytic cleaning process. During and/or after said pyrolytic cleaning process, at least neighbouring areas of the filter are cooled by a cooling air stream and the heating device is supplied with energy from a primary energy source. To prevent the risk of overheating and a potential fire if the primary energy source fails, the appliance is equipped with a secondary energy source, which can be used to generate the cooling air stream, at least if the primary energy source fails.

The invention relates to a cleaning appliance according to the preambleof claim 1.

Cleaning appliances in the present connection, for example, comprise aircleaning appliances, air-conditioning systems and in particular, vacuumcleaners.

Conventional vacuum cleaners operate on the principle that air ladenwith foreign particles is sucked in, filtered in the vacuum cleaner andblown out from the vacuum cleaner in purified form. Since the sucked-inair can contain various foreign particles or foreign bodies, particularrequirements are to be imposed on the filter devices inside the vacuumcleaner. For this reason, it is usual to arrange various filter devicesone after the other in relation to the principal direction of flow ofthe foreign-particle-laden air, where these filter devices fulfilldifferent functions. For example, it is known to collect coarser foreignparticles in a filter bag and to then pass the air flowing out from thefilter bag through a fine-pore filter cloth so that any remaining fineforeign particles can also be filtered out before the air is blown outinto the atmosphere. The pore size of the respective filter device mustbe suitably selected for such a functional allocation to the individualfilter devices.

In order to filter out very fine foreign particles from the air,so-called HEPA (High Efficiency Particulate Air) filters are frequentlyused in vacuum cleaners. These mostly consist of a glass fibre compositewhich is disposed in a support material, for example, paper. Very smallparticles damaging to health, especially allergy-triggering substancescan be removed from the air to be blown out by means of these HEPAfilters. These substances include, for example, pollen, fungi and mitesor their metabolic products or constituents.

Although good results are achieved using these HEPA filters, it isnevertheless to be considered as disadvantageous that the filters havean expensive structure and must be exchanged after a certain operatingtime because they are contaminated. It is also known to use filters madeof ceramic material. An example of a vacuum cleaner with a ceramicfilter device is disclosed in WO 01/41619 A1.

In connection with ceramic filter devices, it has already been suggestedin an unpublished patent application to use such a filter which can becleaned pyrolytically, that is by heating. Ceramic foams consisting ofaluminium dioxide, for example, are suitable for this purpose.

The term ceramic filter device is to be understood in the presentconnection as any filter device which is provided in a cleaningappliance for air to be cleaned to flow through. In connection withvacuum cleaners, the ceramic filter device can, for example, form apreliminary, main or final filter device. At the same time, it isespecially also possible for the ceramic filter device to formcompletely or partly a dust collecting container which replaces aconventional filter bag. Furthermore, a ceramic filter device providedaccording to the invention can additionally or alternatively replace aconventional HEPA filter.

In the generic cleaning appliances it is provided to clean pyrolyticallyat least one ceramic filter inside the cleaning appliance. For thispurpose the heating device provided in the cleaning appliance heats theceramic filter to 400° C. or higher. However, the maximum limitingtemperature at an ABS part provided adjacent to the filter must notexceed 90° C. for example and 110° C. at a PP part for example. Thus,sections of the housing adjacent to the filter are cooled during andafter the pyrolytic cleaning by a cooling air stream which can beproduced, for example, by means of the main drive motor of the cleaningappliance which is supplied by the primary energy source in the same wayas the heating device. In this case, in known solutions it is absolutelyessential that the cleaning appliance is supplied up to the end of thecooling process by the primary energy source, which can be formed inparticular by the public power supply without being restricted thereto.If the primary energy source fails, for example, because a user pullsthe mains plug prematurely, as a result of the lack of cooling,overheating can occur in the device and result in a fire in the worstpossible case.

It is the object of the invention to further develop generic cleaningappliances such that any overheating or a fire can be reliably avoidedif the primary energy source fails during or (shortly) after a pyrolyticcleaning of the filter.

This object is solved by the features of claim 1.

Advantageous embodiments and further developments of the invention areobtained from the dependent claims.

The cleaning appliance according to the invention builds on the genericprior art by the fact that a secondary energy source is provided whichcan be used to generate the cooling air stream at least if the primaryenergy source fails. By means of this solution the cooling air streamrequired to avoid overheating or a fire can be generated in any case,even if the primary energy source fails. A failure of the primary energysource is to be understood in this connection as any state in which therequired cooling air stream cannot be generated without the secondaryenergy source although a cooling air stream is required.

In specific embodiments of the cleaning appliance according to theinvention, it can be provided that the secondary energy source comprisesa fuel cell. In this connection so-called “mini fuel cells” areespecially considered. These mini fuel cells can deliver a power outputof 50 W or more, for example, with a space requirement and weight as forconventional batteries or rechargeable batteries.

Additionally or alternatively, it can be provided that the secondaryenergy source comprises an energy storage device, especially an energystorage device which is charged by the primary energy source. In thesimplest case, the energy storage device can be formed, for example, byconventional disposable batteries.

In especially preferred embodiments of the cleaning appliance accordingto the invention, it can however be provided that the energy storagedevice is formed by a rechargeable battery which is charged by acharging device supplied by the primary energy source. Possiblerechargeable batteries in this context are commercially available typesof batteries, especially lithium ion cells. In many cases, an electricalfast charger can advantageously be used as charging device.

Furthermore, in preferred embodiments of the cleaning applianceaccording to the invention it is provided that the cooling air stream isgenerated by at least one fan at least if the primary energy sourcefails. The at least one fan is preferably a fan provided separately fromthe drive motor of the cleaning appliance.

If is furthermore preferred if a control and/or regulating device isprovided, especially a control and/or regulating device which controlsthe fan. The control and/or regulating device can in this caseespecially comprise a microprocessor and at least in certain embodimentsit can also be provided for controlling or regulating the normaloperation of the cleaning appliance.

In this context it is preferred that the control and/or regulatingdevice controls the charging device. This solution is especiallyconsidered when the charging device comprises a electrical fast charger.

In a preferred further development of the cleaning appliance accordingto the invention it is provided that current temperature information issupplied to the control and/or regulating device. The currenttemperature information preferably relates to the temperature in theareas adjacent to the filter since the temperature in these areas is thefirst to reach critical values if the primary energy source fails.

In this case, it is preferably provided that the current temperatureinformation is obtained by means of at least one temperature sensor. APt 100, for example, is considered as a temperature sensor.

A likewise advantageous further development of the cleaning applianceaccording to the invention provides that information on the currentstate of the secondary energy source is supplied to the control and/orregulating device. For this purpose, for example, the initial voltage ofa rechargeable battery forming the secondary energy source can be tappedand supplied to the control and/or regulating device. In this way, thecharging process of the rechargeable battery can be optimised amongother things.

It is also considered to be advantageous if it is provided thatinformation on the current state of the primary energy source issupplied to the control and/or regulating device. This in particularallows the control and/or regulating device to directly detect a failureof the primary energy source and introduce suitable measuresimmediately, especially by activating the fan.

Independently thereof, it can be provided that the control and/orregulating device controls the heating device. For example, the controland/or regulating device can control a control circuit associated withthe heating device, in the form of a driver circuit, for example, inorder to adjust suitable temperatures for the pyrolytic cleaning innormal operation depending on the output signal of one or moretemperature sensors.

A particularly preferred further development of the invention providesthat the control and/or regulating device only activates the heatingdevice for carrying out a pyrolytic cleaning of the filter when thesecondary energy source can provide sufficient energy for generating thecooling air stream. Whether the secondary energy source can providesufficient energy for generating the cooling air stream can bedetermined, for example, by monitoring the charging state of arechargeable battery forming the secondary energy source.

For all embodiments of the invention it is preferred that the filter isa ceramic filter. The advantages explained initially are achieved usingthe ceramic filters currently available. However, the invention isfundamentally also applicable to filters made of different material ifthese filters are cleaned by pyrolysis.

A likewise preferred further development of the invention provides thatthe capacity of the secondary energy source is at least so large thatthe maximum stored thermal energy in the filter during a pyrolyticcleaning process is released to the surroundings by means of the coolingair stream. The required cooling time is determined according to thesize or the mass of the filter used and the specific heat capacity c.The quantity of heat is calculated using Q=c*m*Δt. For example, for aceramic filter a temperature change At of 400° C. and a mass of about0.75 kg can be assumed. The specific heat capacity of ceramic, between0.8 and 1.2, thus yields a quantity of heat Q of 360 kJ. If a desiredcooling time is about 60 min and the conversion 1 Wh=3.6 kJ, theelectrical power is calculated as 100 Wh/2 h=50 W. This would, forexample, require a rechargeable battery storage device of about 24 typeSub C cells (capable of delivering between 1.2 and 2.4 Ah) (=24*1800mAh*1.2 V).

The basic idea of the invention is to be able to maintain cooling evenwhen the power is interrupted at an unsuitable time. In this way, inmany cases it is possible to dispense with secondary safety devices (forexample, warning lamps or signalling devices) which would otherwise needto be provided for thermal cleaning processes of the ceramic filter. Auser of the cleaning appliance according to the invention need not takeany special precautionary measures although high temperatures must beproduced in the cleaning appliance during the pyrolytic cleaning of thefilter. In an especially advantageous fashion the energy storage deviceof the secondary energy source can be charged in any normal cleaningprocess if its charging state requires this.

A preferred embodiment of the invention is now explained as an examplewith reference to the drawings.

In the figures:

FIG. 1 is a schematic block diagram of the relevant section of acleaning appliance according to the invention.

FIG. 1 only shows the components of a cleaning appliance in the form ofa vacuum cleaner important for the understanding of the invention. Thevacuum cleaner has a ceramic filter 10 which is disposed in a filterhousing 32. The filter housing 32 can be constructed integrally with theremaining vacuum cleaner housing (not shown). Provided adjacent to theceramic filter 10 is a heating device 12 which is indicated in the formof a heater coil. The filter housing 32 has an air inlet 34 and an airoutlet 36. Further air inlets and air outlets not shown can optionallybe provided for the actual cleaning operation. Located in the area ofthe air inlet 34 is a fan 24 by which means a cooling air stream 16 canbe produced in the direction shown by the arrows. Also located in thefilter housing 32 is a temperature sensor 28 which, for example, cancomprise a temperature sensor of the type Pt 100. In the case shown, aprimary energy source 18 is formed by the public power supply network sothat the cleaning appliance according to the invention can be suppliedwith energy in the usual fashion by means of a mains cable. A controlcircuit 30 for the heating device 12 is furthermore provided. Thecontrol circuit 30 can comprise, for example, a driver circuit or thelike. A secondary energy source is provided in the form of arechargeable battery 20 which can be charged by a fast charger 23. Acontrol and/or regulating device 26 controls or regulates the operationof the cleaning appliance, where only the signal leads provided witharrows which are important for the understanding of the invention areshown.

In normal operation the cleaning appliance shown is supplied with energyby means of the power supply 18 forming the primary energy source. Forexample, after a pre-determined number of operating hours has beenreached or it is established as a result of pressure losses that thefilter 10 needs to be cleaned, the control and/or regulating device 26activates the heating device 12 by means of the control circuit 30. Theheating device 12 heats the filter 10 for example to 400° C. or higherfor the purpose of pyrolytic cleaning. In order that ABS and PPcomponents of the filter housing 32 provided adjacent to the filter 10are not heated above temperatures of 90° C. or 110° C., during or afterthe pyrolytic cleaning of the filter 10 a cooling air stream is passedbetween areas of the filter housing 32 at risk and the filter 10. Innormal operation of the cleaning appliance this cooling air stream canoptionally be generated by devices other than the fan 24. Before thecontrol and/or regulating device 26 triggers the pyrolytic cleaning ofthe filter 10, in the embodiment shown it checks the charging state ofthe energy storage device 20 which, in normal operation of the cleaningappliance, is charged by means of the fast charger 22 likewisecontrolled by the control and/or regulating device 26. As an additionalsafety measure the control and/or regulating device 26 only triggers thecleaning process of the filter 10 when the current charging state of theenergy storage device 20 ensures that the required cooling air stream 16can be generated in any case if the primary energy source 18 fails.

It is assumed hereinafter that the user of the cleaning appliancedisconnects the cleaning appliance from the mains 18 at the point whenthe filter 10 has been heated by the heating device 12 to the maximumtemperature of 400° C. or more. Since the control and/or regulatingdevice 26, as shown, is also connected to the supply leads provided forconnection to the mains 18, the control and/or regulating device 26immediately detects that the primary energy source 18 has failed. Inresponse thereto, the control and/or regulating device 26 activates thefan 24 which immediately generates the cooling air flow shown 16. In thecase shown the control and/or regulating device 26 controls the fan 24as a function of temperature information supplied by the temperaturesensor 28 so that a closed control circuit is formed. As soon as thetemperature detected by the temperature sensor 28 has fallen tonon-critical values, the control and/or regulating device 26 deactivatesthe fan 24 since there is no longer a risk of overheating or a fire atthis point.

The features of the invention disclosed in the preceding description, inthe drawings and in the claims can be important for the implementationof the invention both individually and in arbitrary combination.

REFERENCE LIST

10 Filter

12 Heating device

14 Adjacent areas

16 Cooling air stream

18 Primary energy source

20 Secondary energy source

22 Charging device

24 Fan

26 Control and/or regulating device

28 Temperature sensor

30 Control circuit

32 Filter housing

34 Air inlet

36 Air outlet

1-15. (canceled)
 16. A vacuum cleaner, comprising a filter andcomprising a heating device by means of which the filter can be heatedto carry out a pyrolytic cleaning process, wherein at least one ofduring and after said pyrolytic cleaning process of the filter, at leastneighboring areas of the filter are cooled by a cooling air stream andwherein the heating device is supplied by a primary energy source,wherein a secondary energy source is provided which can be used togenerate the cooling air stream at least if the primary energy sourcefails.
 17. The vacuum cleaner according to claim 16, wherein thesecondary energy source comprises a fuel cell.
 18. The vacuum cleaneraccording to claim 16, wherein the secondary energy source comprises anenergy storage device which is charged by the primary energy source. 19.The vacuum cleaner according to claim 18, wherein the energy storagedevice includes a rechargeable battery which is charged by a chargingdevice supplied by the primary energy source.
 20. The vacuum cleaneraccording to any one of the claim 19, wherein a control regulatingdevice is provided which controls the charging device.
 21. The vacuumcleaner according to claim 16, wherein the cooling air stream isgenerated by at least one fan at least if the primary energy sourcefails.
 22. The vacuum cleaner according to claim 16, wherein a controlregulating device is provided which controls the fan.
 23. The vacuumcleaner according to claim 22, wherein current temperature informationis obtained by means of at least one temperature sensor and supplied tothe control regulating device.
 24. The vacuum cleaner according to claim22, wherein information on the current state of the secondary energysource is supplied to the control regulating device.
 25. The vacuumcleaner according to claim 22, wherein information on the current stateof the primary energy source is supplied to the control regulatingdevice.
 26. The vacuum cleaner according to claim 22, wherein thecontrol regulating device controls the heating device.
 27. The vacuumcleaner according to claim 26, wherein the control regulating deviceonly activates the heating device for carrying out a pyrolytic cleaningof the filter when the secondary energy source can provide sufficientenergy for generating the cooling air stream.
 28. The vacuum cleaneraccording to claim 16, wherein the filter includes a ceramic filter. 29.The vacuum cleaner according to claim 16, wherein the capacity of thesecondary energy source is at least so large that the maximum storedthermal energy in the filter during a pyrolytic cleaning process isreleased to the surroundings by means of the cooling air stream.
 30. Avacuum cleaner, comprising: a filter housing; a ceramic filter disposedwithin the filter housing; a heating element disposed within the filterhousing and heating the filter to pyrolytically clean the filter; and afan generating a cooling air flow through the filter housing and coolingat least part of the filter housing adjacent the ceramic filter.
 31. Thevacuum cleaner according to claim 30, further comprising: an electricalconnection receiving power from a primary energy source and powering theheating element; a secondary energy source powering the fan.
 32. Thevacuum cleaner according to claim 31, wherein the secondary energysource includes a rechargeable battery that is charged by power receivedfrom the primary energy source.
 33. The vacuum cleaner according toclaim 31, further comprising a control regulating device controlling thefan and the heating element.
 34. The vacuum cleaner according to claim33, further comprising a temperature sensor measuring the temperaturewithin the filter housing and providing a temperature signal to thecontrol regulating device.
 35. The vacuum cleaner according to claim 33,wherein the control regulating device is connected to the primary energysource and receives a primary signal indicating if the electricalconnection is connected to the primary energy source, and the controlregulating device is connected to the secondary energy source andreceives a secondary signal indicating the power level of the secondaryenergy source.
 36. The vacuum cleaner according to claim 35, wherein thecontrol regulating device only activates the heating element forpyrolytically cleaning of the filter when the secondary energy sourcehas a sufficient power level to power the fan.
 37. The vacuum cleaneraccording to claim 30, wherein the heating element heats the filter to atemperature of at least 400 degrees Celsius.
 38. A method for cleaningthe filter of a vacuum cleaner comprising a filter disposed within afilter housing, a heating element disposed within the filter housing, afan, and a secondary energy source, the method comprising the acts of:connecting the vacuum cleaner to a primary energy source to providepower for the vacuum cleaner; heating the filter with the heatingelement to pyrolytically clean the filter; and generating a cooling airflow through the filter housing with the fan to cool at least part ofthe filter housing adjacent the ceramic filter.
 39. The method accordingto claim 37, wherein the heating element is powered by the primaryenergy source and the fan is powered by the secondary energy source.